The present invention is directed to an inflatable device and method for use in orthopedic procedures to treat bone, and in particular to an improved device and method for reducing fractures in bone and treatment of the spine.
Medical balloons are commonly known for dilating and unblocking arteries that feed the heart (percutaneous translumenal coronary angioplasty) and for arteries other than the coronary arteries (noncoronary percutaneous translumenal angioplasty). In angioplasty, the balloon is tightly wrapped around a catheter shaft to minimize its profile, and is inserted through the skin and into the narrowed section of the artery. The balloon is inflated, typically, by saline or a radiopaque solution, which is forced into the balloon through a syringe. Conversely, for retraction, a vacuum is pulled through the balloon to collapse it.
Medical balloons also have been used for the treatment of bone fractures. One such device is disclosed in U.S. Pat. No. 5,423,850 to Berger, which teaches a method and an assembly for setting a fractured tubular bone using a balloon catheter. The balloon is inserted far away from the fracture site through an incision in the bone, and guide wires are used to transport the uninflated balloon through the medullary canal and past the fracture site for deployment. The inflated balloon is held securely in place by the positive pressure applied to the intramedullary walls of the bone. Once the balloon is deployed, the attached catheter tube is tensioned with a calibrated force measuring device. The tightening of the catheter with the fixed balloon in place aligns the fracture and compresses the proximal and distal portions of the fractured bone together. The tensioned catheter is then secured to the bone at the insertion site with a screw or similar fixating device.
As one skilled in the related art would readily appreciate, there is a continuing need for new and innovative medical balloons and balloon catheters, and in particular a need for balloon catheter equipment directed toward the treatment of diseased and damaged bones. More specifically, there exists a need for a low profile, high-pressure, puncture and tear resistant medical balloon, that can be used to restore the natural anatomy of damaged cortical bone.
The present invention is directed to an inflatable device for use in restoring the anatomy of diseased or fractured bone such as for treatment of the spine. In one embodiment, the inflatable device is a balloon-tipped catheter. The catheter and/or balloon may be varied in size, shape, or configuration according to the desired application. The device may be deployed in any type of bone where collapsed fractures of cortical bone may be treated by restoring the bone from its inner surface. Examples of such bones include, without limitation, vertebral bodies, long bones, the distal radius, and the tibial plateau. Additionally, the inflatable device may also be adapted for use as a spinal prosthesis. For instance, a balloon of the present invention may be designed and configured to replace a vertebral disk, or may serve as a distraction instrument and implant for intervertebral fusion.
The invention is constructed in a manner specialized to restore the anatomy of a fractured bone which has sufficient normal cancellous volume to contain the device. The device is constructed for controlled deployment and reliability at pressures between about 40 to about 400 psi, more preferably at between about 200 to about 300 psi, and most preferably at about 250 psi. The present invention comprises a balloon catheter device in which the inflatable vessel comprises a puncture and tear resistant balloon.
In one embodiment, the inflatable device has a layer of puncture and tear resistant material. In another embodiment, the balloon has multiple layers or coatings of material. The layers or coatings may be applied to achieve a desired shape, feel, performance, or appearance. For instance, layers may be provided to achieve a desired texture, surface characteristic, or color. Examples of surface characteristics include a high or low friction surfaces, and regions of the device capable of providing enhanced gripping to help anchor the device or position it as it is inflated. The outer layer or coating of the inflatable device also may be either hydrophobic or hydrophillic, depending on the degree of xe2x80x9cwetabilityxe2x80x9d desired.
In another embodiment, the invention comprises a rigid catheter which allows for the placement and deployment of the balloon tipped catheter without internal structural reinforcement. This provides the catheter with surprising advantages, including improved surgical control over placement of the balloon tip and rotational control over the balloon during deployment.
The shape of the inflatable device and/or catheter may be curved, shaped or otherwise configured to allow for an easier approach to the bone cavity or to correspond to the portion of the bone which is to be restored. In one embodiment, an axial balloon is constructed with a uniform bulge and blunt distal end to allow the deployment of the balloon against the wall of the prepared bone cavity, and to facilitate uniform expansive pressure in the cavity when inflated. In another embodiment, an offset balloon of circular cross section is employed, while another embodiment uses an offset balloon with a non-circular cross section. In another embodiment, the balloon may be curved to correspond to the interior wall of the cortical bone. In yet another embodiment, a shape memory catheter is used to better position the inflatable device within right or left bones, or in the left or right side of bones that possess a sagittal plane of symmetry.
One embodiment uses a plurality of offset balloons on a single catheter. Deployment and deflation of the balloons can be varied according to the surgical procedure performed by the surgeon. In one embodiment, the plurality of balloons are deployed to restore the cortical bone. Then, one or more balloons is selectively deflated so that bone filler material may be injected into the region previously occupied by the balloon. Once the bone filler has sufficiently gelled or hardened in this region, the remaining balloon or balloons similarly may be deflated and the bone filled.
In one embodiment, the region occupied by the deployed balloon is filled with bone filler at the same time that the balloon is being deflated. Preferably, the rate at which the region is filled with bone filler material is approximately the same rate at which the balloon is deflated so that the volume of the treated region within the bone remains approximately the same.
In yet another embodiment, the cavity may be treated with a sealing material prior to or after deployment of the balloon. The use of a sealant may assist in reducing or preventing leakage of filler material from the cavity, or to prevent bone materials or body fluids from leaching into the cavity. Generally, sealants comprising fibrin or other suitable natural or synthetic constituents may be used for this purpose. The sealant materials may be delivered to the cavity walls by spray application, irrigation, flushing, topical application, or other suitable means, including applying sealant materials to the balloon exterior as a coating. The sealant, also, may be placed inside the treated area first, and then an inflatable device may be used to push the sealant outward toward the cavity walls.
Additionally, the bone cavity may be irrigated and/or aspirated. Irrigation media may comprise saline, water, antibiotic solution or other appropriate fluids to wash the bony interior and release debris. Aspiration of the bone cavity may be used to help clear the bone cavity of bony debris, fatty marrow, and blood products that may prevent adequate dispersal of filler material or that may constrict the cavity. Each of the steps of applying a sealant, irrigating and aspirating may be considered optional, and may be performed after inflation of the balloon, or before, or not at all.
The invention also relates to a method for reducing bone fractures comprising forming a cavity within a damaged bone, inserting the inflatable device into the cavity, inflating the device so that it restores collapsed or deteriorated portions of the cortical bone, preferably returning the bone approximately to its natural anatomy. In a preferred embodiment, a cavity is created in the portion of the bone in which the device is to be deployed and inflated. In one embodiment, the cavity is irrigated before the device is inserted into the bone in order to remove bone marrow and cancellous bone from the area where the device will be inflated. The inflatable device is inserted into the bone and positioned so that inflation of the balloon will assist in restoration of the cortical bone. Once the cortical bone has been sufficiently restored, the balloons may be deflated either in succession or altogether. Bone filler may be added to the region previously occupied by the balloon. Alternatively, the balloon or balloons may be deflated and bone filler injected simultaneously as described in the embodiments above.
In another embodiment, the inflatable device may remain inside the patient for an extended period after the surgical procedure is completed. In one embodiment, the inflatable device remains inside a treated bone. The inflatable device also may be adapted for disk replacement. An inflatable device for disk replacement may be designed to be biologically resorbable while leaving filler material in place or may remain indefinitely. The present invention may be further adapted for use as a distraction device and synthetic allograft spacer for intervertebral fusion.